What is BMR?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain basic physiological functions like breathing, circulation, cell production, and brain function. It represents the minimum energy needed to keep your body alive. BMR accounts for 60-75% of total daily calorie burn. It's the foundation for calculating Total Daily Energy Expenditure (TDEE) and determining calorie needs for weight management.
Enter your age, gender, weight in kilograms, and height in centimeters, then click Get result to see your BMR in calories per day. No sign-up required. Use it for weight management, nutrition planning, or understanding your metabolic rate.
How to use this BMR calculator
Enter your age in years. Select your gender (male or female—formulas differ slightly). Enter your weight in kilograms (1 kg = 2.2 lbs). Enter your height in centimeters (1 cm = 0.394 inches). Click Get result to see your BMR in calories per day. The calculator uses the Mifflin-St Jeor equation, considered the most accurate BMR formula. BMR is the calories burned at rest; multiply by an activity factor to get total daily calorie needs.
Understanding BMR
BMR represents calories burned for basic life functions: breathing, blood circulation, cell production, brain and nerve function, protein synthesis, and maintaining body temperature. It's measured under strict conditions: complete rest, fasting, and thermoneutral environment. BMR decreases with age (metabolism slows), increases with muscle mass (muscle burns more calories than fat), and is higher in men than women (men typically have more muscle mass).
BMR vs TDEE
BMR is calories burned at rest. TDEE (Total Daily Energy Expenditure) is total calories burned including activity. TDEE = BMR × Activity Factor. Activity factors: Sedentary = 1.2, Light = 1.375, Moderate = 1.55, Active = 1.725, Very Active = 1.9. To maintain weight, eat calories equal to TDEE. To lose weight, eat fewer calories than TDEE. To gain weight, eat more calories than TDEE. BMR is the starting point for all these calculations.
Factors affecting BMR
Age: BMR decreases with age (about 2% per decade after 30). Gender: Men typically have higher BMR (more muscle mass). Weight: Heavier people have higher BMR (more tissue to maintain). Height: Taller people have higher BMR (more surface area). Muscle mass: More muscle = higher BMR (muscle is metabolically active). Genetics: Some people naturally have higher or lower BMR. Hormones: Thyroid function affects BMR significantly.
Applications of BMR
BMR is used for weight management (determining calorie needs for weight loss/gain), nutrition planning (calculating daily calorie requirements), fitness goals (understanding metabolic rate), medical assessment (evaluating metabolic health), and diet planning (designing appropriate calorie intake). Understanding BMR helps make informed decisions about calorie intake and weight management strategies.
Tips for accurate BMR calculation
Use accurate measurements: weigh yourself in the morning after using the bathroom, measure height without shoes. The Mifflin-St Jeor equation is most accurate for most people. BMR is an estimate—individual variation exists. For precise BMR, consider indirect calorimetry (medical test). Remember BMR is calories at rest—add activity to get total needs. Consult a healthcare provider or dietitian for personalized nutrition plans based on BMR.
Summary
This BMR calculator calculates your Basal Metabolic Rate using the Mifflin-St Jeor equation. Enter age, gender, weight, and height, then click Get result to see BMR in calories per day. It's free, works in your browser, and requires no account. Use it for weight management, nutrition planning, or understanding metabolic rate. BMR is the foundation for determining daily calorie needs—multiply by activity factor to get Total Daily Energy Expenditure (TDEE).